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The early sporogonic cycle of Plasmodium falciparum in laboratory-infected Anopheles gambiae: an estimation of parasite efficacy
- Source :
- Tropical Medicine & International Health, 3, 1, pp. 21-28, Tropical Medicine & International Health, 3, 21-28
- Publication Year :
- 1998
-
Abstract
- This study investigated the successive losses in the parasite densities of Plasmodium falciparum stages during the early sporogony in laboratory-reared Anopheles gambiae infected by membrane feeding with blood from naturally infected gametocyte carriers (>50 gametocytes/mm3). The developmental stages of P. falciparum in the mosquito were studied from zygote to oocyst, by immunofluorescent method using monoclonal antibodies against the Pfs25 protein present on the surface of newly formed gametes. This method allows for assessment of the various sporogonic stages before, during and after passage of the midgut wall. Parasite densities were determined within the entire blood meal at 3 h (zygotes and macrogametes) and 24 h (ookinetes) post-infection. At 48 h after the mosquito blood meal, midguts were checked for the presence of early oocysts. For the mid-size oocysts count, classic microscopy examination was used at day 7 postinfection. The parasite efficacy was estimated by following successive losses in parasite densities between different early stages of the sporogonic cycle in A. gambiae. Thirty-seven experimental infections were realized with high gametocyte densities, ranging from 64 to 2392 gametocytes/mm3. All gametocyte carriers showed infection with round forms 100%; ookinetes were found in 91.9%. The prevalences of infections with oocysts were 48.6% at day 2 (young oocyst) and 37.8% at day 7 (mid-size oocyst). The mean densities per mosquito for each parasite stage were 12.6 round forms, 5.5 ookinetes, 1.8 young oocyst and 2 mid-size oocysts. Significant correlations were found between two consecutive parasite stages (round forms/ookinetes, ookinetes/young oocysts, young oocysts/mid-size oocysts) and between round forms and mid-size oocysts. The mean parasite density significantly decreased between round forms and ookinetes (yield Y1 = 41.6%) and between ookinetes and young oocysts (Y2 = 61.4%). By contrast, no significant decrease was observed between young oocysts and mid-size oocysts (Y3 = 91.2%). The overall yield of the early sporogonic cycle (from round form to oocyst at day 7) was equal to 25.7%, indicating that almost 3/4 of the total parasites were lost during the early step of the sporogonic cycle, from 3 h post-infection to day 7.
- Subjects :
- Anopheles gambiae
Plasmodium falciparum
DEVELOPPEMENT BIOLOGIQUE
gastheer-parasiet interactie [Malaria]
parasite-host interaction [Malaria]
Microbiology
Apicomplexa
CAPACITE VECTORIELLE
parasitic diseases
Anopheles
Gametocyte
Parasite hosting
Animals
Humans
Malaria, Falciparum
Child
biology
fungi
VECTEUR
Public Health, Environmental and Occupational Health
ELEVAGE DE LABORATOIRE
INFECTION EXPERIMENTALE
PALUDISME
biology.organism_classification
Blood meal
Virology
Insect Vectors
Infectious Diseases
Carrier State
Protozoa
DYNAMIQUE DE POPULATION
Parasitology
TAUX DE SURVIE
AGENT PATHOGENE
Subjects
Details
- ISSN :
- 13602276
- Database :
- OpenAIRE
- Journal :
- Tropical Medicine & International Health, 3, 1, pp. 21-28, Tropical Medicine & International Health, 3, 21-28
- Accession number :
- edsair.doi.dedup.....04384f059e7bce2de13f08ff77d4f046